joined the betanet test and got some coins , now I want to make sure that the test coin is valuable after the release of the main network?
From the BetaNet page
"You are connecting to the Nimiq Beta Testnet. Testnet Mining does not create permanent Nimiqs.
The Testnet and your Nimiq balance may be reset at any time until the release of the Nimiq Mainnet."
The coins you mined on the BetaNet is just a test... they have no value now, or later.