Can I stop using Vive later if I change my mind?

You can always stop with Vive. For asset management, this is easier; you can always withdraw or pause. Withdrawing from the pension account is more difficult, as you are bound by a number of tax rules. Pension is traditionally locked until your retirement age (that is the deal for the tax benefit). If you do wish to withdraw this (to cash), a penalty will apply. Transferring to another annuity (3rd pillar pension) provider is possible without any loss.