Strictly speaking, the only Church membership spoken about in the New Testament refers to the act of placing a new believer into the Body of Christ. This happens the moment a person is saved.
1 Corinthians 12:27 (New International Version) Now you are the body of Christ, and each one of you is a part of it.
Ephesians 5:30 (New International Version) For we are members of His body.
We are happy to receive anyone into fellowship who confesses Jesus Christ as their personal Saviour and Lord and has a consistent Christian life and testimony.
Being received into fellowship means that you are ready to embrace the privileges of local church life and are willing to accept responsibilities. These include regular attendance when possible; using your gift(s) for the up-building of other in the Church; submitting to one another and coming under the covering the Spiritual oversight in the church; and sharing as the Lord enables you in the financial needs of the local church as an act of worship.
Malachi 3:10 (New International Version) Bring the whole tithe into the storehouse, that there may be food in My house. Test Me in this, “says the LORD Almighty,” and see if I will not throw open the floodgates of heaven and pour out so much blessing that you will not have room enough for it.